Beyond the mechanics of the Klyuchevskoy group, this study is important because it shows that seismic features frequently inferred to
represent magma storage zones are dynamic in time. Prominent features appear and disappear on the scale of years. We propose that
sponge-like magma reservoirs filled with melt can be caused by the
rapid migration of fluids through overheated crustal rocks. In turn, the
fluid migration is triggered by variations in the stress field and quickly
facilitated by the highly fractured nature of volcanic crust. Following
eruptions, the fluid deficit and the relaxation of fracture pathways
may decrease the melt content leading to the temporary disappearance
of seismic anomalies in the V
p/Vs images. A similar concept of a spongelike network of interconnected fractures and melt bodies beneath
volcanoes is envisaged by Lu and Dzurisin (2010) based on surface deformation observations.